1. Field of the Invention
This invention relates generally to a control mechanism for the selection of weft yarns in rapier looms provided with presenting needles on presenting levers. Specifically, the control mechanism is controlled by a system of levers from a series of electromagnets.
2. Prior Art
Various mechanisms exist for the selection of weft yarns in rapier looms. The selected weft yarn must be clamped, cut off and presented to the rapier and, once gripped by the rapier, inserted into the shed.
Before that the various possible weft yarns, each run through an eye of the respective presenting needles. These presenting needles are connected to levers, shafts, hook elements, etc., which together form a mechanism which is controlled in one way or another to make the selected presenting needle move with its corresponding weft yarn for the presentation of the weft to the rapier.
The object of the invention is such a control mechanism. The problem with such a mechanism lies in the high speed at which rapier looms are currently running, requiring a quick response for presentation of the new weft yarn and for the withdrawal of the previous presenting needle.
There are such mechanisms in existence in which each lever, controlling its corresponding presenting needles is on one side continuously under the tensile force of a spring and thus inclined to bring the presenting needle in question back to its rest position, and on the other side cyclically under pressure of a resilient pressure finger which is pushed in by a cam disk and held in this position by an electromagnet for the time that an electric current flows through it, in accordance with the requirements of the fabric.
However, this control mechanism lacks reliability regarding control, particularly the high speeds which are presently used in rapier looms.